CLOUDS are an interesting phenomenon. Minuscule droplets form around impurities in the air, such as dust and industrial chemical wastes. They then join together in countless numbers to form a cloud. From my office window I look out on a 56-story building, a mass of glass and steel. Occasionally the top of this skyscraper is obscured by a low cloud. Dense as the cloud is, I know the building is still there, the occupants carrying on their normal routine. The structure hasn't been suddenly decapitated just because it's hidden by a cloud. Do we occasionally let another kind of cloud obscure some of our highest concepts and ideals? Tiny impurities in thought--particles of jealousy, fear, anger, hatred, and so forth sometimes build up until they present us with thunderclouds of trouble. They seem to threaten a relationship, cast shadows on our health, endanger a career. It's important, then, to avoid such cloud buildup by dispelling these thought particles as soon as they appear in our mental atmosphere. Christ Jesus alerted his hearers to eliminate impurities of thought when he told them: ``The light of the body is the eye: if therefore thine eye be single, thy whole body shall be full of light. But if thine eye be evil, thy whole body shall be full of darkness. If therefore the light that is in thee be darkness, how great is that darkness!'' 1 Much of Jesus' Sermon on the Mount,2 from which this passage comes, tells us how to deal with such impurities. He stresses the need to replace anger with love, sensuality with purity, and revenge with forgiveness. The pure thought expressed by Jesus in his ministry enabled him to heal and to help others remove, through divine power, impurities that took form in disease and other kinds of discord. He helped his disciples to meet anxiety with calmness and anger with healing. Mary Baker Eddy, who discovered and founded Christian Science, writes, ``Hold thought steadfastly to the enduring, the good, and the true, and you will bring these into your experience proportionably to their occupancy of your thoughts.'' 3 As God's offspring, man is as pure and perfect as his creator. This is the truth of our being. It is natural for us, then, to have pure, loving thoughts, thoughts that emanate from the one divine Mind. This isn't a naive standpoint. It's eminently realistic. Pure, spiritually based thinking is expressed in useful, satisfying activity, in a life filled with love. Holding to the fact that man is always in God's lo ving presence sustains us as we strive to stay with God-given thoughts and to put out destructive, sensuous thinking. It's interesting that at the heart of a severe storm there can be an area of calm, the eye of the storm, as it is called. We need to stay mentally in the calm of God's presence when faced by stormy situations. God is always present and supremely powerful. In reality there is no evil power to create impurities in man. We can begin to discern this in prayer and to prove it. When divine Truth and Love dispel the clouds of hate and fear, we see something of the real man shining forth in all his perfection. Just as a building remains intact though partially hidden by mist, so man remains intact. He never really changes but exists at the standpoint of perfection throughout eternity. It is our privilege, through purification of thought, to bear witness to this truth. 1 Matthew 6:22, 23. 2 See Matthew, chapters 5-7. 3 Science and Health with Key to the Scriptures, p. 261.